Belgium’s late-June heatwave caused 2,112 more deaths than normal, far exceeding Sciensano’s forecasts and affecting not only older people but also working-age men.
Sciensano’s detailed analysis found that between 18 June and 12 July there were 2,112 excess deaths, equal to a relative excess mortality of 31%. That was the highest number of additional deaths and the highest relative excess mortality recorded during any major heat episode since 2000. The August 2020 heatwave ranks second, with 1,597 excess deaths and excess mortality of 28%.
Whereas heat-related deaths in earlier heatwaves were usually concentrated among older women, the June 2026 heatwave had a broader impact. Sciensano found markedly higher excess mortality among older men as well, something that had also been seen in August 2020.
For the first time, however, excess mortality was also recorded among working-age men. On average, each death linked to the heatwave was associated with 11.8 years of life lost. Men aged 45 to 64 accounted for much of that figure, with an average of 24.6 years of life lost per death in that group alone.
The impact also varied by region. Wallonia was hit harder, with the district of Liège standing out, while lower excess mortality was recorded on the coast and in the west of the country. That uneven geographical pattern could be explained in part by risk factors such as higher night-time minimum temperatures and ozone levels, but not entirely. Sciensano noted, for example, that the district of Tongeren had similar values to Liège but lower excess mortality.
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The institute also found that actual mortality exceeded what its scientific forecasting model had predicted. The model, trained on data from the past 23 years, took account of temperature, ozone levels and duration of exposure. It had projected just over 1,700 excess deaths, but the observed toll, especially over the weekend of 27 and 28 June, was significantly higher. More than 400 additional deaths remain unexplained.
Health Minister Frank Vandenbroucke said work was already under way on a new heat plan. He said the current Heat and Ozone Plan, which mainly focuses on phases and communication, lacks key elements of a full preparedness strategy.
Vandenbroucke said he wants an integrated, inter-federal Heat-Health Preparedness and Response Plan ready by summer 2027. According to him, it should include pre-arranged measures, clear responsibilities, capacity planning and operational playbooks for all sectors involved.
He added that extreme heat is not only a public health issue. “This is an issue for society as a whole, and so political leaders at every level and across many different sectors must work together on it.”
